S yntrophus

Abstract

Syn.tro'phus. Gr. masc. n. syntrophos companion, nourished with one or brought up with; N.L. masc. n. Syntrophus one living syntrophically with another so that each produces a nutrient required by the other. Desulfobacterota / Syntrophia / Syntrophales / Syntrophaceae / Syntrophus Cells are rod shaped with rounded ends, 0.5–0.8 µm × 1.0–2.0 µm. Occur singly and in pairs. Gram‐stain‐negative. Endospores not formed. The type species is motile by means of monotrichous polar flagella in the early stage of growth; other species are nonmotile. Strictly anaerobic and chemoorganotrophic. Possesses a fermentative type of metabolism. Crotonate is fermented by all species, whereas aromatic compounds such as benzoate gentisate, hydroquinone, and cinnamate are only fermented by some species. Some substrates, such as benzoate or fatty acids, are only oxidized in the presence of H 2 /formate‐utilizing methanogenic or sulfate‐reducing partner prokaryotes. Some species can grow in the presence of crotonate as electron acceptor and also as electron donor for benzoate reduction to cyclohexane carboxylate. Substrate oxidation is incomplete and leads to acetate production. Sulfate, sulfite, thiosulfate, sulfur, and nitrate are not used as electron acceptors. Cells contain cytochromes and menaquinones. Mesophilic. Optimal growth temperature, 28–37°C. Neutrophilic. Optimal growth pH, 7.1–7.4. Occur in anoxic freshwater sediment or sludge from anaerobic wastewater treatment facilities. DNA G + C content (mol%) : 51.5–54.6 ( T m , Bd, genome). Type species : Syntrophus buswellii Mountfort, Brulla, Krumholz and Bryant 1984, 216 VP .